Arthritis is inflammation of one or more body joints. It results in pain, swelling, stiffness, and limited movement.
Arthritis involves the breakdown of cartilage. Cartilage normally protects the joint, allowing for smooth movement. Cartilage also absorbs shock when pressure is placed on the joint. Without cartilage, the bones would rub together, causing pain, swelling (inflammation), and stiffness.
When the cartilage becomes worn or damaged, or is lost due to disease or trauma, the joint no longer has a painless, mobile area of motion. The body attempts to make up for the lost cartilage. It produces fluid in the joint lining (synovium), which tries to act like a cushion, like water in a waterbed. But it also causes the joint to swell and restricts motion. The swelling causes stretching of the joint covering (capsule), which causes pain.
Synovial Fluid formation-